Heeeeey lemlister! 👋
Usually, if replies are not tracked, it's because you use a Gmail alias to send an email, but you haven't configured the forward to receive an email back from the alias.
💡 You can check this article to add the forward in Gmail.
💡 Also, you can have a look at those two articles about tracking
If you need more precision, I'll be happy to exchange on the chat my lemlister!